William Francis FORBES-SEMPILL, alias Lord SEMPILL, Master of SEMPILL: British. SEMPILL, an aeronautical engineer, served with distinction in the First World War in the Royal Flying Corps, Royal Naval Air Service and fledgling RAF, from which he retired in 1918. He remained involved in the aviation and aeronautical fields. From 1920 to 1923 he headed a civilian mission to Japan engaged in training Japanese aviators. He maintained close touch with Japanese missions and officials throughout the 1920's and 1930's. Before and during the war he was associated with a number of Fascist or semi-Fascist individuals and organisations, including 'Action', 'The Link', and the 'Constitutional Reform Association'. There is circumstantial evidence that in the1920's and 1930's Sempill passed sensitive military and technical information to the Japanese. For reasons touched on but not fully explained, Sempill was not prosecuted under the Official Secrets Acts, though this was seriously considered in 1925. On the evidence of these files, Sempill's activities on behalf of the Japanese and his Fascist contacts were motivated less by any desire to help the enemy or to make money than by his own impetuous character, obstinacy, and flawed judgement